First, I understand if you need to know a lot more about the content. Basically we interviewed her mom about her life growing up in rural communist Hungary, what school and work were like. We then transitioned into their decision to leave, and how that process worked out. Asked the refugee camp in Austria and how they got to the US. Her father (wife's grandfather) was very old when she was born, and was born in 1889. He served in both wars according to my mother in law. So we asked a bit about that too but I feel we need to verify a lot of that. We plan on interviewing my father-in-law too.
What makes a personal story valuable for research? Should this mainly be viewed as a family history account, or could it be useful to others? If it would be valuable to others, what types of questions are best, and how do I make it widely available for research?
The thing about historic research is that the research that isn't affected by personal interest, agenda etc is the really old stuff.
To counter this one must read/hear the same story several times from different sources to even be able to suggest that was the case.
One couples story wont stop the local historical institute's press but I would think that if you do just alittlebit of digging you will probobly be able to find some researcher/auther that is wrighting about just that subject. They will surely be happy about it!
On what type of questions you should ask I can only give a somewhat of a dumb answer. Ask every question you can think of. The reason is that we don't know for what end the material will be used for. Maby it will be studied to give a picture about hungarian refugees during that time, maby about the communist regime. Maby about serving in both great wars. The subject could be one in a million so just let the questions flow. The longer and more detailed the more valuable it will be.
Edit: I myself actually did a paper once on the Swedish volonters in the Finnish Winter War, more specificly, how the individual soldier percieved the war. As you can tell I had to research alot of personal notes, letters etc and even though each story didn't hold much worth on their own they where a bliss to study and together they formed a factual and gripping story
Alot of libraries and community organizations use these interviews for oral history projects. If there's a Hungarian American organization out there they might be interested in having the interview in their archive for research and/posterity.
For example: https://www.hungaryfoundation.org/memory-project/